/Engine/Source/Runtime/Serialization/Public/Backends/JsonStructDeserializerBackend.h
The returned string contains debug information that is relevant to the reader's serialization format. For example, it could be a line and column number for text based formats, or a byte offset for binary serialization formats.
The debug string.
virtual [FString](API\Runtime\Core\Containers\FString) GetDebugString() const